McCullum testified Cairns twice asked him to get involved in spot-fixing in 2008 - approaches he did not report to the International Cricket Council's anti-corruption unit for three years, a delay he justified in court by saying "it's not easy ratting on someone I regarded as a mate".

That delay attracted criticism, with McCullum claiming Justice Nigel Sweeney cast aspersions on his evidence when summing up, instructing the jury they had to believe two of the three key prosecution witnesses in order to convict Cairns.

"The more I read about what he's telling the jurors, the more my heart sinks," wrote McCullum.

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Chris Cairns was found not guilty of perjury and perverting the course of justice.

"Sweeney tells the jury, among other things, that they have to believe two out of the three main witnesses against Cairns in order to find him guilty. Sweeney then goes on to completely and utterly discredit two of those witnesses, Lou Vincent and his ex-wife, Elly.

"Paraphrasing Sweeney, Elly was presumably so drunk she didn't know what she was saying, and Lou's evidence, though he has been banned from cricket for life for match fixing, can be written off in respect of anything he's said about Cairns as the rambling lies of a troubled soul.

"From the moment Sweeney rubbishes Lou and Elly's evidence, the die is cast."

McCullum was surprised the jury had to believe two of the witnesses.

"Sweeney, to my uneducated ears, appears to be telling the jury that if they believe me and disbelieve Cairns, they still cannot convict him, if they also disbelieve Lou and Elly.

"I simply don't understand why the jury cannot disregard Lou and Elly's evidence if they don't believe it, and still reach a verdict based on whether they believe me or Cairns.

"I'm not saying that would happen — in my opinion, Sweeney casts aspersions on my evidence too — but if I'd known at the outset what the equation was going to be, two out of three, it would have been a fairly compelling reason not to bother going to London, not to put myself and my family through this crap."

Brendon McCullum — Declared. Written in collaboration with Greg McGee. Published by Mower Books, an imprint of Upstart Press Ltd. RRP $49.99. On sale from today.